Channelizer
Understanding Channelizers
Digital channelization has revolutionized wideband receiver design. By digitizing the entire band and extracting channels digitally, channelizers provide flexibility, programmability, and simultaneous multi-channel capability that analog approaches cannot match.
| Antenna Type | Gain (dBi) | Beamwidth | Bandwidth |
|---|---|---|---|
| Dipole | 2.1 | 360° (H) | Moderate (~10%) |
| Patch | 5-8 | 60-90° | Narrow (2-5%) |
| Horn | 10-25 | 10-60° | Wide (>50%) |
| Parabolic | 25-45 | 1-10° | Wide |
Channelizer Architectures
- Polyphase filterbank (PFB): Efficient FIR filter implementation that simultaneously outputs all channels. Most common for uniform channelization.
- FFT-based: Uses FFT to separate channels. Fastest for large channel counts. Frequency resolution = sample rate / FFT length.
- Tunable DDC (Digital Down-Converter): Selects individual channels at arbitrary frequencies. Most flexible but requires more resources per channel.
Frequently Asked Questions
What is a channelizer?
A channelizer digitally divides a wideband spectrum into narrower channels using polyphase filterbanks or FFT processing. It replaces analog filter banks with flexible digital processing, enabling reconfigurable multi-channel reception.
How many channels can a channelizer implement?
Modern FPGAs can implement 1000+ channels from a 1 GHz bandwidth. The channel count is limited by FPGA resources and ADC sample rate. A 4 GSPS ADC with polyphase filterbank can produce thousands of 1 MHz channels simultaneously.
What is the advantage over analog channelization?
Digital: reconfigurable (change channel widths on the fly), simultaneous (all channels available always), lower SWaP, and no analog filter drift. Analog: lower latency, no quantization noise, simpler for a few channels.